Mechanism of SO2 adsorption on receptor sites incorporated into porous SiO2 films

Abstract

SO2 adsorption on porous SiO2 films containing alkylamine sites is considered. Alkylamine-SO2 complexes are modeled using the molecular mechanics method; it is demonstrated that the SO2 molecule is adsorbed on the amine-containing group of alkylamine. On the basis of these computations, the alkylamine fragment responsible for SO2 adsorption was determined, and quantum chemical calculations of the electronic structure and complexation energies depending on the number of ethyl substituents in the alkylamine were performed. The dipole moment of the alkylamine-SO2 complex is shown to differ strongly in its magnitude from the geometric sum of dipole moments of component molecules. The reasons for the difference are charge transfer to SO2 and charge redistribution in the alkylamine with decreasing electron density on hydrogen atoms.